A Biomechanical Model of the Inner Ear: Numerical Simulation of the Caloric Test

Shuang Shen,Xiuzhen Sun,Shen Yu,Wenlong Liu,Yingxi Liu,Yingfeng Su,Wei Zhao

doi:10.1155/2013/160205

Shuang Shen, Xiuzhen Sun + Show 5 more

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https://doi.org/10.1155/2013/160205

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Abstract

Whether two vertical semicircular canals can receive thermal stimuli remains controversial. This study examined the caloric response in the three semicircular canals to the clinical hot caloric test using the finite element method. The results of the developed model showed the horizontal canal (HC) cupula maximally deflected to the utricle side by approximately 3 μm during the hot supine test. The anterior canal cupula began to receive the caloric stimuli about 20 s after the HC cupula, and it maximally deflected to the canal side by 0.55 μm. The posterior canal cupula did not receive caloric stimuli until approximately 40 s after the HC cupula, and it maximally deflected to the canal side by 0.34 μm. Although the endolymph flow and the cupular deformation change with respect to the head position during the test, the supine test ensures the maximal caloric response in the HC, but no substantial improvement for the responses of the two vertical canals was observed. In conclusion, while the usual supine test is the optimum test for evaluating the functions of the inner ear, more irrigation time is needed in order to effectively clinically examine the vertical canals.

Highlights

The caloric stimulation test has been widely used to examine vestibular performance in clinical medicine
Yagi et al [4] reported that caloric nystagmus contains vertical and torsional components and posited that their origins are the posterior and superior semicircular canals
The utriculo-endolymphatic valve (UEV) opening is assumed to be located in the anteroinferior wall of the utricle, and the utricle is assumed to be separate from the saccule [19,20,21,22,23]

Summary

Introduction

The caloric stimulation test has been widely used to examine vestibular performance in clinical medicine. This procedure uses thermal irrigation of the ear canal with cold and/or hot fluid (water or air) to elicit a vestibular signal. Yagi et al [4] reported that caloric nystagmus contains vertical and torsional components and posited that their origins are the posterior and superior semicircular canals. Neither the posterior nor superior semicircular canal was observed to receive a caloric effect by Ichijo [1] and Ichijo [8] These studies indicate that the vertical and torsional components originate in the horizontal canal (HC). According to Aoki et al [9], among 200 ears, 50% exhibited no vertical component of the caloric response, 45% exhibited a small upbeating component, and 5% exhibited a small downbeating component

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